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The U-Boot Driver Model Project
===============================
Keyboard input analysis
=======================
Marek Vasut <marek.vasut@gmail.com>
2012-02-20
I) Overview
-----------
The keyboard drivers are most often registered with STDIO subsystem. There are
components of the keyboard drivers though, which operate in severe ad-hoc
manner, often being related to interrupt-driven keypress reception. This
components will require the most sanitization of all parts of keyboard input
subsystem.
Otherwise, the keyboard is no different from other standard input but with the
necessity to decode scancodes. These are decoded using tables provided by
keyboard drivers. These tables are often driver specific.
II) Approach
------------
The most problematic part is the interrupt driven keypress reception. For this,
the buffers that are currently shared throughout the whole U-Boot would need to
be converted into driver's private data.
III) Analysis of in-tree drivers
--------------------------------
1) board/mpl/common/kbd.c
-------------------------
This driver is a classic STDIO driver, no problem with conversion is expected.
Only necessary change will be to move this driver to a proper location.
2) board/rbc823/kbd.c
---------------------
This driver is a classic STDIO driver, no problem with conversion is expected.
Only necessary change will be to move this driver to a proper location.
3) drivers/input/keyboard.c
---------------------------
This driver is special in many ways. Firstly because this is a universal stub
driver for converting scancodes from i8042 and the likes. Secondly because the
buffer is filled by various other ad-hoc implementations of keyboard input by
using this buffer as an extern. This will need to be fixed by allowing drivers
to pass certain routines to this driver via platform data.
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